DF CI 10.5, DF 4 and DF 7

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  • Created by: A.B.
  • Created on: 01-12-13 14:12
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  • DF Catalysts and altering octane numbers CI 10.5, DF 4 and DF 7
    • A catalyst speeds up a chemical reaction but is not used up in the reaction -> this process is called catalysis
    • Heterogeneous catalysts are in a different physical state to the reactants.
    • In a catalytic converter platinum or rhodium act as heterogeneous catalysts for the following reaction:
    • To increase octane number (decrease tendency to auto ignite)
      • Cracking
        • A shorter, branched alkane and an alkene are usually formed
        • A zeolite is used as a catalyst
      • Reforming
        • Alkanes are converted to cycloalkanes and hydrogen
        • Cycloalkanes are converted to arenas and hydrogen
        • In terms of octane numbers, arenas > cycloalkanes > alkanes
      • Isomerisation
        • Zeolite not catalyst but sieve to separate branched and unbranched isomers.
        • Platinum catalyst

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